Pigtail fob



W. A. READY March 8, 193 2.

' Filed April 24, 1930 Patented Mar. 8, 1932 UNITED STATES PATENT OFFICEv WILLIAM A. READY, 0F BROOKL INE, MASSACHUSETTS PIGTAIL FOR VARIABLEELECTRIC CIRCUIT TUNING DEVICES Application filed April 24,

invention illustrated by the drawings I have shown a variable aircondenser equipped with a flexible constant inductance member which Ishall hereafter refer to as a pigtail 1. While I have illustrated theuse of my invention in connection with a condenser substantially thesame in construction as shown and more fully described in my United.States Letters Patent No. 1,756,570, it should be understood that theigtail may be used with the same improved results in connection withvariometers, variocouplers, etc.

Thec'ondenser shown in the drawings is of the short wave type and has arotor which comprises the plates 2 and the shaft 3, and a stator,comprising fixed plates 4 (portions only of which are shown in Figs. 1and y 2) and a frame 5 (a portion only of which is shown). The rotorshaft 3 is shown with one end mounted for rotation in an adjustablebearing 6.

While the piiigtail 1 may be mounted in a number of di erent ways, Ihave shown a simple and compact manner of doing so in connectionwith acondenser. The shaft 3 and bearing 6 are bored axially and one end ofthe pigtail 1 is s'oldered or otherwise secured to the rotor at theinner end of the bore 7, while the other end is soldered to a terminalmember 8 securedto'the frame 5.

.Thus, I have secured the pigtail, which 1930. Serial No. 446,967.

and a terminal, but so far as I am aware no one has ever used a constantinductance pigtail. Heretofore, the type of pigtail used and itsassembly were such that the inductance of the pigtail varied as therotor was turned. Thisvchange in inductance of the pigtail affects thecircuit and prevents securing accuracy in adjustment which is essentialas, for instance, in so-called short wave radio apparatus. curaciesandpermit precision adjustment ofa variable circuit tuning device that Ihave invented my constant inductance pigtail.

I have found that by arranging the flexible wire (pigtail) in a straightline and using 5 braided or stranded wire the wire merely twists aboutan axis without changing the inductance effect in the igtail.

As a result of my invention, I secure a direct and positive electricalconnection between a wire 9 in a circuit and the rotor. Furthermore, therotation of the rotor to adjust the circuit does not change theinductance of the pigtail, because of the fact that the effectiverelation of the pigtail to the surrounding energized parts does notchange. This results in more accurate and easier adjustment of a givencircuit, because by hav-' ing the inductance of the pigtail 1 constantit cannot affect or interfere with the changes sirable, because it willprevent contact of the pigtail 1 with either the shaft 3 or the frame 5.If the pigtail 1 should contact with the shaft 3 or frame 5 intermediateits fixed ends, a sort of short-circuiting effect would take place andthereby change the inductance of the Pigtail 1.

While I haveillustrated and described a preferred'embodiment of myinvention, I do not wish to be limited thereby, because the scope of myinvention is best defined in the 05 following claims. Claims v 1. Anelectric circuit tuning device having a rotor, a frame supporting therotor, a

flexible" electrical conductor of fixed induc- It is to correct theseinac- 6o Ill) tance connecting the rotor and a terminal supported by theframe, said flexible conductor being located in line with the axis ofthe rotor, thereby to twist throughout its length to prevent capacitychanges in the rotor, and an insulating material surrounding saidflexible conductor to prevent contact wigh the rotor or frameintermediate its fixed en s.

2. In a variable electric circuitv tuning device, a flexible pigtailconductor constructed and arranged to provide a constant inductancetherein at all times, and an insulator surrounding said'flexibleconductor to prevent short-circuiting thereof with the said device.

3. An electric circuit tuning device having a rotor, a frame supportingthe rotor, a terminal secured to said frame, means providing a bore insaid frame and in said rotor, a constant inductance flexible conductorlocated in said bore and having one end fixed to said rotor and theother end being fixed to said terminal, and an insulating tubular sleevelocated in said bore and surrounding said flexible conductor between itsfixed ends.

In testimony whereof, I have signed my name tothis specification.

WILLIAM A, READY.

